The present invention relates to an input/output device for connection and disconnection of active lines, and particularly to a device for connecting and disconnecting other electronic circuit devices to and from a network of signal circuits operating independently of an operating system bus, without causing the operation of the system bus to stop.
In recent computer systems, as well as high speed and high performance processing devices, there has also been a demand for improvements in the transfer rate of a system bus which is the transmission path for the results of processing. Also, accompanying the diversification of systems, there has been an increasing necessity to connect electronic circuits having various functions mainly to the system bus. The roles played by computer systems have become much more serious, and in order to maintain expansion devices including the aforementioned electronic circuits, there is a tendency to not permit system stoppages, and a need has arisen to connect or disconnect these expansion devices using active lines. On the other hand, in shared bus system type configurations, there is also a need for a way of settling the bus signal waveform quickly, for each expansion device, in order to achieve high speed operation.
Conventionally, as disclosed in Japanese Patent Laid-open Publication No. Hei 5-12777 (which will be referred to as publication 1), there has been known a device in which power is supplied beforehand using a cord, etc., and disable control (open control) of bus drivers is carried out. As disclosed in Patent laid-open publication No. Hei 4-171520 (publication 2) a power supply and an open/close control line of a driver are connected to bus circuits by a long pin, while other bus signal lines are connected to the bus circuits by a short pin. At the time of insertion of a device, corruption of signals on the bus caused by the insertion is prevented by disabling the open/close signal line of the drivers in advance. However, in publication 1, the procedure of connecting the cord beforehand at the time of insertion or removal is complicated, while in publication 2 an open/close control line must be disabled beforehand. In either case, since it can not be guaranteed that the drivers will be disabled when insertion or removal is carried out carelessly, there is a possibility of problems arising such as the system crashing, for instance.
The object of the present invention is to provide an input/output device capable of connecting and disconnecting active lines, and particularly an input/output device in which the insertion or removal of expansion devices does not inhibit bus signal transfer of other electronic devices on a high speed bus due to a disabled state being maintained at the time of insertion or removal using transfer gates with small signal delay in the input output device.
Another object of the present invention is to provide an input/output device capable of connecting and disconnecting active lines, and particularly an input/output device in which the internal power supply systems of expansion devices are multiplexed, the influence on power supplies is reduced at the time of inserting or removing expansion devices, at the same time as ensuring that the maintaining of high impedance of internal parts of the expansion devices, particularly the input/output devices, does not become unreliable, and in which the operation of electronic circuits not involved with insertion or removal does not become unreliable.
Still another object of the present invention is to provide a method, related to an input/output device, that can be applied to a high speed bus to rapidly settle the bus operating waveform by arranging insertion of transfer gates at locations a fixed short distance from a bus at the input/output section of electronic circuits.
An input/output device of the present invention is connected to a plurality of electronic circuits and to a plurality of signal circuit networks having signal branch wires, these electronic circuit networks being arranged on printed circuit boards interconnecting the signal circuit networks and on separate expansion devices, the expansion devices having an input/output device power supply section for supplying power to the input output devices and being connected to the signal circuit networks through connectors including a pair of long pins that make initial contact at the time of insertion and are the last thing separated at the time of removal, and a pair of short pins that make contact after the long pins at the time of insertion, and are separated before the long pins at the time of removal, the input/output device power supply section being connected to a main power supply through the pair of long pins, the input/output device including a plurality of transfer gates, the transfer gates having two input/output terminals and an open/close control terminal, one of the input terminals of the plurality of transfer gates being connected to the plurality of signal branch wires through the pair of short pins while the other input terminal of the plurality of transfer gates is connected to the electronic circuits, and the open/close control terminal is connected to a positive or negative power supply of the input/output device power supply section inside the expansion devices, through a resistor.
Further, an input device of the present invention is characterized in that the open/close control terminals of the plurality of transfer gates are connected to a control device for carrying out open/close control of the transfer gates, through the pair of long pins.
The control device of the present invention drives the open/close terminal in synchronism with a reference signal used by the electronic circuits to extract signal of the signal circuit networks.
Further, the control device of the present invention has connection confirmation means for confirming whether or not the plurality of expansion devices are connected to the signal circuit networks, and at least one connection state register for establishing connection states of the plurality of expansion devices that have been identified by the connection confirmation means.
The control device of the present invention is further characterized in that it has an open/close control register, and open and close for each input/output device is controlled by writing open or closed information to a region of the open/close control register corresponding to each input/output device.
An expansion device of the present invention has an input/output device power supply section for supplying power only to the input/output device, and a circuit power supply section for supplying power to circuits other than the input/output device, the input/output power supply section being connected to a main power supply through a first pair of long pins, the circuit power supply section being connected to the main power supply or to a different reserve charge power supply through a second pair of long pins.
The expansion device of the present invention is further characterized in that it has an input/output device power supply section for supplying power only to the input/output device, and a circuit power supply section for supplying power to circuits other than the input/output device, the input/output power supply section being connected to a main power supply through a first pair of long pins, the circuit power supply section being connected to the main power supply through a second pair of long pins.
The expansion device of the present invention is further characterized in that it has an input/output device power supply section for supplying power only to the input/output device, and a circuit power supply section for supplying power to circuits other than the input/output device, the input/output power supply section being connected to a main power supply through a first pair of long pins, the circuit power supply section being connected to a capacitor through a second pair of long pins, the capacitor being charged by the main power supply.
Still further, the input/output device of the present invention is characterized in that the capacitor is charged from the main power supply through a resistor, or through a resistor and a diode.
Further, in the input/output device of the present invention, a circuit power supply section is connected to the main supply through a pair of short pins.
An expansion device of the present invention is characterized in that the input/output device power supply section and the circuit power supply section are wired onto a printed substrate for connecting the electronic circuits, between spaces where there is no wiring material.
The expansion device of the present invention is further characterized in that a pin on a connector for supplying power to the input/output device power supply section and the circuit power supply section are arranged with maximum separation on the connector.
The input/output device of the present invention is connected to a plurality of electronic circuits and to a plurality of signal circuit networks having signal branch wires, and includes a plurality of transfer gates. The transfer gates have two input/output terminals and an open/close control terminal. First signal branch wires connect one input/output terminal of the transfer gates and the signal circuit networks, while second signal branch wires connect the other input/output terminals of said plurality of transfer gates to the electronic circuits. The open/close control terminal of the transfer gates maintains a potential across the two input/output terminals to always maintain a conductive state. Reflected waves of the signal circuit networks are reduced by making the length of the first signal branch wires less than 1.5 inches, and distribution loss of the electronic circuits is reduced by making the length of the second signal branch wires less than 1.5 inches.
Since the present has the above construction, a disable signal is supplied to the open/close control terminal of the transfer gates at the same time as a stable power supply is provided to the transfer gates, even when expansion devices are inserted or removed, the input/output terminals of the transfer gates are maintained at high impedance, and it is possible to minimize the effects on the system bus at the time of insertion or removal.
Further, in the present invention, a reserve charge power supply other than the main power supply for supplying power to a plurality of expansion devices is prepared, and the power supply systems inside the expansion devices are arranged into stable power supply systems connected to a stable main power supply from initial insertion of the expansion devices and unstable power supply systems connected to the reserve charge power supply at the time of insertion of the expansion devices. From initial insertion of the expansion devices, by supplying power to transfer gates that require the input/output terminals to be reliably high impedance from the stable power supply systems and supplying power to charge a capacitive load existing in the expansion devices from the unstable power supply systems, it is possible to reduce the effects on the main power supply and to continue stable operation of other expansion devices currently operating on the system bus, even at the time of insertion or removal of the expansion devices. As long as the main power supply can supply power smoothly it can also serve as the reserve charge power supply.
Also, by inserting transfer gates at positions fixed short distances from a bus at the input output section of the electronic circuits, the effects of reflections of the transfer gates at the electronic circuit side can be absorbed by the transfer gates, bus signal multiplexed reflected waves can be attenuated in a short time, and the bus waveform can be settled rapidly.